Correct Gear

Up to 45mph use Drive. (Around town). Above 45mph use OverDrive.

Less heat generated in tranny.

What Bill says.... D = Drive (D)= Overdrive

General rule of thumb is that you can't hurt anything but fuel economy leaving it in D, but you can over heat or strain the transmission in rare cases in (D)..

I've got a 95 blazer and if I'm going less than 30 mph I'll usually lock it in

mac

Please remove splinters before emailing

You will never hurt or strain anything not using OD other than maybe loose a bit of MPG (but even that depends on your axle ratio and tire size too) Cars lived for many years and went many many miles too without even having a OD tranny. Actaully, in some ways, OD is more strain on tranny and engine than drive because it has to handle higher average input torque to use it because same power is still needed to power car down the road and this is accomplished with a higher torque at a lower RPM to deliver the same required HP to rear wheels.

----------------- TheSnoMan.com

I have a 1989 s10 with a western 6ft plow.

I have been plowing snow with it since 1994 and I Have yet to use ( D ) I use overdrive at all time except when backing up.

I bought the truck NEW in 1988 with 8 miles on Speedo

Same Tranny , Which has the Same tranny fluid & Filter that was in it when I bought it. and the truck has 198,000 miles on it .

That is because the tranny has more torque capacity than your engine can produce. Even if you have a 4.3, it is not much of a challange for a 700R4 to handle. New heavy SUV's with tall gears and V8's and higher weights have basically same tranny with electronic controls. Late model 700R4's were some of the most relaible 4 speed OD automatic trannies GM ever built. I have one in a heavy burb that has over 180K on it and it has not had a easy life and it still works like new so a good lifespan for a 700R4 is not that rare.

----------------- TheSnoMan.com

Thanks for the replies. It is much clearer now. Hopefully I haven't done any damage to my transmission by driving in the incorrect gear.

I'd say that damage would be unlikely.. Most owners manuals will say to not use overdrive (D) under a certain MPH in traffic or whatever, but most folks just leave it in (D) and let the transmission downshift to D if needed..

Also, a clue that you should put it in D is when you're driving in (D) and the transmission wants to shift up and down a lot as you're driving... It's called "hunting", which means that the transmission is hunting for the right gear for the driving condition.. Usually, you'll notice it shifting down when you touch the accelerator and shifting back up when you ease up..

mac

Please remove splinters before emailing